A bit confused here now...
Since saes posted about the beeping either being a CPU that needs reseated, the fan on the heatsink not working properly, or the heatsink not in proper contact with that processor, you're going to buy a new power supply?
Other than possibly giving more power to the fan (Though the RPM wire on it would restrict it from going any faster than it wants to due to temperature), a new power supply wouldn't do anything, as far as I know.
And no, giving more power to your system would not reduce lag. Unless you are adding more power so you can upgrade your hardware components.